1. Field of the Invention
The present invention relates to random number generating methods and apparatus. More particularly, the present invention relates to methods and apparatus for generating nonreproducible, nonperiodic random numbers using electrical noise.
2. Description of the Related Art
Random numbers are useful for a variety of different applications. For example, computer-implemented simulations that model physical objects can receive streams of random numbers as input data to assist in predicting how simulated objects may react or behave in the real world. Random numbers are also useful in the field of data security, where data can be encrypted by combining it with a sequence of random numbers. Decryption of the encrypted data requires knowledge of the sequence of random numbers used for encryption. Thus, the encrypted data remains secure as long as the random numbers used for encryption cannot be ascertained.
Conventionally, random numbers have been generated using known recursive algorithms and techniques, such as the linear congruential method and the additive congruential method. Under these methods, an algorithm uses an arbitrarily-selected initial number, known as a "seed," to produce a first random number. The algorithm then uses each new random number to generate other random numbers.
These conventional random number generators, however, do not produce truly random numbers, but rather "pseudo-random" numbers. Once the algorithm and the seed are known, the numbers produced therefrom are deterministic and thus reproducible.
Also, the algorithms used in the conventional random number generators often produce a series of numbers that eventually repeats. While pseudo-random numbers may be acceptable for a few applications, their use is often less than satisfactory. For example, pseudo-random numbers used in data encryption can be readily reproduced by identifying patterns in encrypted data due to the repetitive nature of pseudo-random numbers. Once the pseudo-random numbers have been reproduced, the encrypted data can be easily decrypted. Thus, it is desirable to generate random numbers that are not reproducible or periodic.